- To determine if imatinib mesylate versus hydroxychloroquine (HCQ) and imatinib mesylate is more effective in terms of BCR/ABL levels in patients with chronic myeloid leukemia in major cytogenetic response (MCyR) with residual BCR/ABL-positive cells detectable by quantitative polymerase chain reaction after at least one year of imatinib mesylate treatment.